Venomous vs. Poisonous

As a herpetologist one of my biggest pet peeves is the incorrect usage of the words venomous and poisonous. Another huge pet peeve is calling an amphibian a reptile (but we’ll save that rant for another day ). Most people don’t understand that there is a difference between an organism being venomous or poisonous.

To be venomous an animal must be able to inject a toxin. The common delivery systems are fangs and stingers. The toxin is stored internally usually in a specialized gland(s). A great example of a venomous animal is a rattlesnake. All toxic snakes are venomous and not poisonous, well all of them except one. As with everything in nature there is an exception, the Asian tiger snake is both poisonous and venomous (see below).

Poison on the other hand is a toxic substance that is usually secreted from an organism’s external covering be it skin or leaves. Poisons are not injected instead they have to come in contact with skin or be ingested to cause harm. Poison dart frogs and poison ivy are examples of poisonous organisms.

So the next time someone yells that they’ve been bitten by a poisonous snake you can politely correct them while en route to the nearest hospital unless of course you are in the Asian tiger snake’s range. 😛

Venomous Poisonous

Venomous Poisonous

A paper published in 2007 documented an actual poisonous snake. It turns out that the Asian tiger snake (Rhabdophis tigrinus, AKA Keelback, AKA Yamakagashi), and possibly a few other members of the Rhabdophis genus, is able to sequester toxins from toads it consumes and secrete them from specialized glands in the neck. Snakes of this species that live in toad-free environments don’t have the poison. It seems this snake is also venomous with rear fangs. So this species is a poisonous venomous snake! Read abstract.

Poisonous and Venomous

Asian Tiger Snake eating a toad (c)2007 Wikipedia

*A big thanks to Jim Pearce for informing me about the keelback snake.

Disclaimer: The views expressed in this post are solely this author's and do not necessarily reflect the views of The Wandering Herpetologist website.

I found the information on the “poisonous” garter snakes while researching venomous snakes for home school for my grandsons.
Three species of garter snakes that are cousins to the Asian tiger snake obtain poison in the same way, but store it in their bodies.
The spitting cobra can also be considered “poisonous” since it’s venom acts as an irritant to the skin, and particularly the eyes. I don’t know what result drinking it would have, though.

“Although Garter Snakes simply retain the poisons they acquire from newt prey (tetrodotoxin, abbreviated TTX) in their bodies for some time following a meal, Tiger Keelback snakes actively sequester the poisons they acquire from toad prey (bufotoxins, specifically bufadienolides) in a poison gland on the back of their neck (called the nuchal gland), enabling them to remain poisonous for much longer following a meal. So, basically these four snakes possess two different types of toxins in different places in their bodies, which come from different sources, and serve different purposes.”
“So, if anyone ever asks you how many of the ~3150 species of snakes in the world are poisonous, you can give them an answer of at least four species (Thamnophis sirtalis/couchii/atratus and Rhabdophis tigrinus), with the caveat that they are both poisonous and venomous. Aside from those species, the remaining snakes in the world are either nonvenomous/nonpoisonous or venomous, with constrictors belonging to either of those categories.”http://christopherjrex.hubpages.com/hub/What-is-snake-venom-poison